The lightning port should last as long as you have the phone. If you do experience issues however, I'm almost certain a trip to the store will end in your favor.
Welcome to iMore! It's a darn sturdy port. The lightning port itself can actually hold your iPhone upright with no additional support (exactly how Apple's charging docks are designed). I've been using lightning ports and adapters since the day they came out and have never had one go bad.